Immune Profiling Evaluation of Newly Diagnose Multiple Myeloma (NDMM) Transplant Eligible (TE) Patients Treated with Daratumumab, Cyclophosphamide, Thalidomide and Dexamethasone. Preliminary Results

Background: CD38-targeting antibody Daratumumab (Dara) has been demonstrating significant improvement in (MM) patient's survival. Cyclophosphamide (C), thalidomide (T) and dexamethasone (D) - (CTd) is one of the most used induction protocols worldwide and the MAX-Dara study was the first that combine Dara-CTd as induction for (NDMM) (TE) patients. We hypothesized that this new combo + autologous stem cell transplantation (ASCT) could affect the quantitative recovery of distinct lymphocytes subsets. Objective: Primary endpoint was to quantify lymphocytes subpopulations in (NDMM) (TE) patients at different treatment phases. Secondary endpoint was to evaluate B cells subsets at same times. Methods: Peripheral blood of 10 NDMM TE patients was collected at three different moments: at diagnose, after 4 induction cycles and after two consolidation cycles post- (ASCT). Dara-CTd protocol was for up to four 28-day induction cycles: C-500mg per oral (PO) d 1,8 and 15, T at 100-200mg PO d 1 to 28, Dex at 40mg PO d 1,8,15 and 22 and Dara 16mg/Kg/dose IV on d 1,8,15 and 22 during cycles 1 - 2 and every other week in cycles 3 - 4, followed by ASCT. Consolidation was started at D+30 after ASCT and all patients received up to four 28-day consolidation cycles: Dara 16mg/Kg and (D) at 40mg every other week, associated with T at 100mg PO d 1 - 28. Dara 16mg/Kg was used monthly as maintenance until progression or limiting toxicity. Flow cytometry was used to detect lymphocyte surface by CD3, CD4, CD5, CD8, CD16, CD19, CD20, CD38, CD45 and CD56 in the scatter plot. B cells were isolated and subpopulations (naïve B cells, class and non-class switched memory B cells, , IgD-CD27- memory B cells and plasma blasts) were detected by CD20, CD24, CD27, CD38, CD45 and IgD. Statistical analysis was performed using the SPSS® v25.0. Results: The median number of lymphocytes subsets at diagnosis were 1139 x 10³/μL for T cells, 155 x 10³/μL for B cells and 284 x 10³/μL for NK cells. After four cycles of Dara-CTD the median number of T, B and NK cells had dropped to 834, 7.5 and 8.0 x 10³/μL respectively (p<0.05). After two consolidation cycles post-ASCT, the T cells showed full reconstitution (1246 x 10³/μL) while B cells and NK cells had weakly reconstitution (20 x 10³/μL and 33 x 10³/μL, respectively). Regarding B cells subpopulations, the median B cell naïve numbers decreased from 32 x 10³/μL to 1 x 10³/μL (after 4 cycles), and recovery post-ASCT to 14 x 10³/μL. Class and non-class switched memory B cells numbers decreased after induction from 30 to 3.5 x 10³/μL and 37 to 2.0 x 10³/μL respectively. These subpopulations recovery after ASCT+ two consolidation cycles were not observed. Discussion: Different cells populations expresses CD38 antigen in their surface and depending on that, transitional lymphocytes counts reduction have been shown with different protocols using Dara. The present study confirmed that there is a decrease on total lymphocytes numbers after Dara- use. After two consolidation cycles post-ASCT, T cells counts had been recovered, while NK and B cells had a slightly recovery suggesting that Dara-CTD combination had a slighted negative impact in those lymphocytes' reconstitution. Concerning specifically B cells populations, we found that naive B cell was the first to showed faster recovery, although it was still below the reference range (33 - 259 x 10³/μL). Conclusion: This is the first study that reported lymphocyte profile with Dara plus CTD protocol. The preliminary data suggests that Dara-CTD reduces all lymphocytes populations after induction phase, but after ASCT followed by two consolidations cycles full reconstitution of T cells and slight recovery of B and NK cells was observed. Disclosures De Queiroz Crusoe: Janssen: Research Funding.

Prognostic significance of new biological markers in chronic lymphocytic leukaemia

Introduction. Chronic lymphocytic leukaemia is a disease with heterogeneous clinical course and outcome. Some patients have a progressive course of the disease and require therapy immediately after the diagnosis, while others have a stable form without the need for treatment. Recently, two new biological markers, the expression of CD38 antigen and ZAP-70 have shown independent significance in the prognosis in CLL patients. Objective. The aim of our study was to evaluate the clinical value of CD38 antigen and ZAP-70 expression as predictors of the disease progression and to analyze the correlation of these markers with other B-CLL prognostic markers. Methods. We assessed the expression of CD38 antigens by flow cytometry on peripheral blood samples and the expression of ZAP-70 by immunohistochemistry on formalin-fixed bone marrow (BM) biopsies in 40 newly diagnosed B-CLL patients. Disease progression was defined by the period elapsed from diagnosis to the time to first treatment (TFT). Results. Expression of CD38 antigen correlated positively with ZAP-70 expression (Pearson, r=0.476; p=0.002). Also, correlation analysis results showed that a positive expression of CD38 and ZAP-70 statistically significantly correlated with unfavourable classical prognostic parameters, such as advanced Binet stage C, diffuse BM infiltration, increased lactate-dehydrogenase and beta-2 microglobulin serum levels. Patients with positive expression of CD38 antigen and ZAP-70 had a shorter TFT (log rank, 0.003 vs. 0.049). Conclusion. Both new biological markers were shown to have an exceptional significance in the prediction of prognosis in CLL patients.

Low or Undetectable Numbers of Philadelphia Chromosome Positive (Ph+) Leukemia Cells in the Primitive (CD34posCD38neg) Stem Cell Fraction in Chronic Myeloid Leukemia (CML) Patients during Tyrosine Kinase Inhibitor Therapy.

Targeted tyrosine kinase inhibitors (TKIs) efficiently induce rapid hematologic and cytogenetic remission in most chronic myeloid leukemia (CML) patients. However, in vitro experiments have suggested that the most primitive CML stem cells residing in the CD34posCD38neg fraction are relatively resistant to TKIs. The prevalence of these stem cells in vivo in patients under TKI therapy is unclear. The aim of this project was to analyze the effect of TKI therapy on Ph+ leukemia stem cell pool in patients and to analyze the proportion of Ph+ cells in different stem cell fractions. A total of 26 chronic phase CML patients were included in the study. 18 patients were treated with imatinib, 5 with dasatinib, and 3 with bosutinib. The median time of TKI treatment was 20 months (range 3–72 months). Large volume (median 30 ml, range 5–55 ml) of bone marrow (BM) aspirate was collected and mononuclear cells (MNC) were isolated. CD34pos cells were separated with paramagnetic beads and further sorted into CD34posCD38pos and CD34posCD38neg cell populations with multicolor flow cytometry in order to analyze progenitor cell fractions of different maturation stage. Proportion of Ph+ cells was determined with interphase FISH by counting 1000 cells in each fraction. The median yield of MNCs from 30 ml of BM aspirate was 280x106 cells resulting in a median of 32 000 CD34posCD38neg cells (range 1000–91000). High-sensitivity counting of the proportion of Ph+ cells was feasible with a median number of counted interphase nuclei of 1005. During TKI therapy the CD34pos cells expressing highest CD38 antigen level were already mostly differentiated into B-cell lineage (CD19 positive). The CD34pos cells expressing low CD38 antigen levels expressed markers of more primitive cells such as C-kit (CD117) and CD133. Of 26 patients with CML, 19 were in complete cytogenetic remission (CCyR) when assessed by metaphase FISH of non-fractionated BM cells (1000 cells analyzed). Only 3 patients had single Ph+ cells in CD34pos cell fractions (less than 1%). In remainder of patients, all progenitor cell fractions, including the most primitive CD34posCD38neg cells, were negative for Ph+ cells. 3 patients had 0–1% of Ph+ cells in non-fractionated BM sample. One of them had 0.2% of Ph+ cells in CD34posCD38neg fraction, but the other 2 patients had 0/1000 Ph+ stem cells. 4 patients had a partial cytogenetic response (5–20% of Ph+ cells in non-fractionated BM sample). Again, the proportion of Ph+ cells was not increased in the most primitive CD34posCD38neg cell fraction. Interestingly, patients who had discontinued imatinib treatment had lower level of Ph+ cells in different CD34pos fractions (median 0.1%) when compared to non-fractionated BM (median 9.3%). Based on our data, in chronic phase CML patients, TKI therapy eradicates most Ph+ CD34pos progenitor cells. Unexpectedly, leukemic stem cells were not enriched in the most primitive CD34posCD38neg cell fraction in vivo. These results differ from the in vitro studies, where CD34posCD38neg cells have been shown to be resistant to TKIs. This could be due to non-physiological conditions (growth factor sensitivity, other cytokines) in cell culture assays. In addition, leukemic stem cells in vivo may be located in the subcortical hypoxic stem cell niche in the BM and are less likely to be aspirated. Our data underline the tremendous proliferative potential of very rare stem cells in CML patients in CCyR, as is evident after discontinuation of TKI therapy. Future studies evaluating the kinetics of disappearance of Ph+ cells from stem cell fractions during TKI therapy and the location of residual Ph+ stem cells in the BM are warranted and may give important information on the depth of the therapy response. Furthermore, this knowledge may aid in targeting therapy to these cells and finding curative treatment strategies in CML.

Analysis of CD4+CD25hi Regulatory T Cells in the Peripheral Blood of Patients with B Cell Chronic Lymphocytic Leukemia (CLL).

Introduction: Naturally occurring regulatory T cells (Treg) prevent autoimmune and inflammatory diseases and represent one important factor contributing to the inhibition of antitumor immune response in cancer. CLL is a disease that is characterized both by immunodeficiency and sometimes by autoimmunity. We analyzed the frequency of Treg population in the peripheral blood of patients with B-CLL and correlated them with clinical and laboratory characteristics. Methods: We analyzed prospectively 49 patients with B-CLL (29 males, 20 females) with median age of 63 and 24 normal healthy volunteers. Freshly isolated peripheral blood mononuclear cells were analysed by flow cytometry using the EPICS XL /MSL cytometer (Beckman Coulter Co). We determined the level of apoptosis by the method of annexin-V and the frequency of Treg as cells positive for CD4, CD25hi and intracellular staining of Foxp3 using the PE anti-Human Foxp3 staining set protocol. We recorded clinical information regarding Rai and Binet staging, hematological and biochemical parameters and the presence of autoimmune hemolytic anemia. Results: The level of apoptosis as determined by the annexin V method was significantly lower on CD19+ cells of patients compared to normal controls (4.7 vs11.34 p=0.02). Moreover patients under treatment had significantly lower apoptosis level vs untreated (4vs6.4, p=0.023). The mean and median values of Treg cells in patients with CLL were higher but not significantly compared to controls. However the log10 values of the Treg frequencies were significantly higher in the group of CLL (0.6287vs0.1021, p=0.03). There was not any statistically significant association of Tregs with age, Rai and Binet staging, LDH values, and the level of apoptosis. Patients with levels of Treg cells>mean control value presented lower median expression of CD38 antigen of borderline significance (3.8vs7, p=0,06). 5/26 patients with Treg frequency >median control value presented autoimmune hemolytic anemia compared to 0/18 with Treg <median control value (p=0.06) Conclusion: The log10 values of Treg frequencies in patients with B-CLL were significantly higher compared to normal controls in accordance with previously published data. We did not observe any significant association with any laboratory or clinical characteristics or the level of apoptosis. Patients with Treg levels above the mean control values had a lower although not significantly expression of CD38 antigen indicating an association with more indolent disease. Functional study of these cells will help the interpretation of the data and will shed more light on the their exact role in the pathogenesis of the disease.